In the technical field of washing machines—and in particular in the technical field of laundry washing machines—the use of drawer structures is widely known, which are adapted to contain one or more washing agents, typically a laundry detergent and a softener, which are suited to be dispensed in a metered manner according to operating modes that are predetermined during a work cycle of the machine itself.
More in detail, these structures comprise a hollow shell, in which a drawer is mounted in a movable manner and defines one or more chambers, which are each adapted to act as a tank that is suited to receive the washing agent (laundry detergent or softener), typically in a quantity that is equal to a plurality of doses of said washing agent. Furthermore, the shell containing the drawer is generally mounted on a casing of the laundry machine, so as to be movable between an extracted position and a retracted position relative to the casing. In the extracted position, the chambers of the drawer open up outwards and are adapted to receive said quantity of laundry detergent and/or softener. In the retracted position, on the other hand, the chambers of the drawer are closed by the casing and are suited to dispense the aforesaid quantity of laundry detergent and/or softener during the work cycle through inner ducts of the machine towards the washing tank.
For this type of application, the washing agents used are typically available in a liquid form and, therefore, they are generally dispensed by means of a pumping apparatus, in particular of the hydraulic type. The pumping apparatus usually comprises a pair of electropumps, of which one is adapted to push a quantity of the liquid contained in the laundry detergent chamber, whereas the other one, in turn, is adapted to push a quantity of the liquid contained in the softener chamber. In use, these quantities are equal to the respective doses desired for the work cycle selected, whereas the remaining part of the laundry detergent and softener in the liquid form remains in the respective chambers so as to be used in following work cycles.
The pumping apparatus is generally controlled by an electronic control unit, which is arranged in the washing machine and is configured to be electrically connected to the electropumps so as to cause the laundry detergent and softener to be dispensed according to predetermined operating modes.
According to the prior art, an example of drawer is known, in which the electropumps are mounted inside the chambers and are electrically connected to the electronic control unit by means of a mechanical connection, which is interrupted every time the drawer is moved from the retracted position to the extracted position. Typically, this electric connection is performed by means electric connectors, which have a part that is mounted on the drawer, whereas the other part is mounted on the casing, these parts being able to be engaged and disengaged every time the drawer is moved to the retracted position and removed from the retracted position, respectively.
Though, the aforesaid example has some drawbacks.
One drawback is due to the fact that the electropumps are operatively immersed in the respective washing agents in the liquid form that are housed in the chambers.
This drawback implies not only a remarkable reduction of the liquid loading capacity inside the chambers. In fact, for reasons due to electric safety, manufacturers necessarily have to use an electropump provided with a DC and low-power electric motor, thus making the adoption of a power supplier indispensable, which causes the system to be more complicated. Furthermore, the electric wiring must be performed with expensive solutions, so as to ensure the reliability of the electric connection.
Another drawback is due to the fact that the electric connection is reversible and removable, in particular by means of electric connectors. In fact, the drawer, in use, is frequently moved to the retracted position and removed from it, thus involving a considerable risk that, in time, can lead to the electric connectors being affected by wear, which causes the electric connection between the electropumps and the control unit to be unreliable. This can cause serious faults and failures of the laundry machine.
Also, in the art are known some devices or methods as described in their respective documents.
For example, EP 2251481 A1 discloses a laundry washing appliance comprising a cabinet accommodating a laundry washing tub and a dispensing arrangement for dispensing laundry washing treatment products to be used during laundry washing, the dispensing arrangement comprising: a drawer slidable within a seat provided in the cabinet, the drawer defining at least one container for laundry washing treatment products; at least one suction pump associated with the at least one container and fluidly connected to the laundry washing tub for delivering thereto dosed amounts of the treatment products; suction pipes connected between the at least one suction pump and the at least one container, wherein the at least one suction pump and the suction pipes are arranged so as to enable the suction of the dosed amounts of treatment product from above a surface of the treatment product contained in said container.
EP 2251480 A1 discloses a laundry washing appliance comprising a cabinet accommodating a laundry washing tub and a dispensing arrangement for dispensing laundry washing treatment products to be used during laundry washing. The dispensing arrangement comprises: a drawer slidable within a seat provided in the cabinet, the drawer defining at least one container for laundry washing treatment products; at least one suction pump associated with the at least one container and fluidly connected to the laundry washing tub for delivering thereto dosed amounts of the treatment products; at least one valve for fluidly connecting the at least one container to the at least one suction pump, the valve being realized so as to automatically close and cut off the fluid connection between the at least one container and the at least one suction pump when the drawer is even partially extracted from the seat, and to automatically open and establish the fluid connection between the at least one container and the at least one suction pump when the drawer is pushed into the seat.
DE 102009030329 A1 discloses a method of converting a household cleaning appliance having a single use dispensing system to a bulk dispensing system, wherein the single use dispensing system comprises a dispenser housing in a cabinet of the household cleaning appliance and is fluidly coupled to a treating chamber in the cabinet, and at least one dispensing cup fluidly coupled to the dispenser housing, the method comprising: inserting a bulk dispensing cartridge having a fluid outlet into the at least one dispensing cup; and mounting a metering device with a fluid inlet and a fluid outlet in the cabinet such that the metering device fluid outlet is fluidly coupled to the housing and the metering device fluid inlet mates with the bulk dispensing cartridge fluid outlet when the drawer is in a dispense position thereby establishing a bulk dispensing flow path from the bulk dispensing cartridge to the housing.